TNF-β, a member of the tumor necrosis factor family, is a potent lymphoid factor that exerts cytotoxic effects on a wide range of tumor cells . The biological effects of TNF-β are very similar to TNF-α,due to the similarity of molecular structure and the receptors.As reported, TNF-α could inhibit the proliferation and induce apoptosis of A549 cells,therefore, A549 cells were seeded into triplicate wells of 96-well plates at a density of 4,000 cells/well with 5% serum standard DMEM including various concentrations of recombinant rat TNF-β. After incubated for 48h, cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10 µL of CCK-8 solution was added to each well of the plate, then the absorbance at 450 nm was measured using a microplate reader after incubating the plate for 2 hours at 37℃. Proliferation of A549 cells after incubation with TNF-β for 48h observed by inverted microscope was shown in Figure 1. Cell viability was assessed by CCK-8 (Cell Counting Kit-8 ) assay after incubation with recombinant mouse TNF-β for 48h. The result was shown in Figure 2. It was obvious that TNF-β significantly inhibit cell viability of A549 cells. The ED50 is 2.5μg/ml.

Figure 2. Inhibition of A549 cells proliferation after stimulated with TNF-β